Exhibit 3(i)

                        CERTIFICATE OF AMENDMENT OF THE
                          CERTIFICATE OF INCORPORATION

                                       of

                        REGENERON PHARMACEUTICALS, INC.


               Under Section 805 of the Business Corporation Law
                            of the State of New York


                  We the undersigned, Leonard S. Schleifer, President, and Paul
Lubetkin, Secretary of Regeneron Pharmaceuticals, Inc., a corporation organized
and existing under the laws of the State of New York, in accordance with the
provisions of Section 104 of the Business Corporation Law of the State of New
York, DO HEREBY CERTIFY:

                  1.  The name of the corporation is Regeneron Pharmaceuticals,
Inc. (hereinafter called the "Corporation").

                  2. The Certificate of Incorporation was filed with the
Department of State of the State of New York on January 11, 1988.

                  3. The Certificate of Incorporation of the Company, as
amended heretofore (the "Certificate of Incorporation"), is further amended by
the addition of the following provisions stating the number, designation,
relative rights, preferences and limitations of a series of Preferred Shares of
the Company designated as "Series A Junior Participating Preferred Stock."

                  4. To accomplish the foregoing amendment, a new Article IX is
added to the Certificate of Incorporation, which Article IX reads in its
entirety as follows:


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                                  ARTICLE IX
                                       
                 SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                  Section 1. Designation and Amount. The shares of such series
shall be designated as "Series A Junior Participating Preferred Stock" and the
number of shares constituting such series shall be 100,000.


                  Section 2.  Dividends and Distributions.

                  (A) The holders of shares of Series A Junior Participating
Preferred Stock shall be entitled to receive, when, as and if declared by the
Board of Directors out of funds legally available for the purpose, quarterly
dividends payable in cash on the last day of March, June, September and
December in each year (each such date being referred to herein as a "Quarterly
Dividend Payment Date"), commencing on the first Quarterly Dividend Payment
Date after the first issuance of a share or fraction of a share of Series A
Junior Participating Preferred Stock, in an amount per share (rounded to the
nearest cent) equal to the greater of (a) $0.01 or (b) subject to the provision
for adjustment hereinafter set forth, 1,000 times the aggregate per share
amount of all cash dividends, and 1,000 times the aggregate per share amount
(payable in kind) of all non-cash dividends or other distributions other than a
dividend payable in Common Shares or a subdivision of the outstanding Common
Shares (by reclassification or otherwise), declared on the Common Shares since
the immediately preceding Quarterly Dividend Payment Date, or, with respect to
the first Quarterly Dividend Payment Date, since the first issuance of any
share or fraction of a share of Series A Junior Participating Preferred Stock.
In the event the Corporation shall at any time after October 18, 1996 (the
"Rights Declaration Date") (i) declare any dividend on Common Shares payable in
Common Shares, (ii) subdivide the outstanding Common Shares, or (iii) combine
the outstanding Common Shares into a smaller number of shares, then in each
such case the amount to which holders of shares of Series A Junior
Participating Preferred Stock were entitled immediately prior to such event
under clause (b) of the preceding sentence shall be adjusted by multiplying
such amount by a fraction the numerator of which is the number of Common Shares
outstanding immediately after such event and the denominator of which is 

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the number of Common Shares that were outstanding immediately prior to such
event.

                  (B) The Corporation shall declare a dividend or distribution
on the Series A Junior Participating Preferred Stock as provided in Paragraph
(A) above immediately after it declares a dividend or distribution on the Common
Shares (other than a dividend payable in Common Shares); provided that, in the
event no dividend or distribution shall have been declared on the Common Shares
during the period between any Quarterly Dividend Payment Date and the next
subsequent Quarterly Dividend Payment Date, a dividend of $0.01 per share on the
Series A Junior Participating Preferred Stock shall nevertheless be payable on
such subsequent Quarterly Dividend Payment Date.

                  (C) Dividends shall begin to accrue and be cumulative on
outstanding shares of Series A Junior Participating Preferred Stock from the
Quarterly Dividend Payment Date next preceding the date of issue of such shares
of Series A Junior Participating Preferred Stock, unless the date of issue of
such shares is prior to the record date for the first Quarterly Dividend
Payment Date, in which case dividends on such shares shall begin to accrue from
the date of issue of such shares, or unless the date of issue is a Quarterly
Dividend Payment Date or is a date after the record date for the determination

of holders of shares of Series A Junior Participating Preferred Stock entitled
to receive a quarterly dividend and before such Quarterly Dividend Payment
Date, in either of which events such dividends shall begin to accrue and be
cumulative from such Quarterly Dividend Payment Date. Accrued but unpaid
dividends shall not bear interest. Dividends paid on the shares of Series A
Junior Participating Preferred Stock in an amount less than the total amount of
such dividends at the time accrued and payable on such shares shall be
allocated pro rata on a share-by-share basis among all such shares at the time
outstanding. The Board of Directors may fix a record date for the determination
of holders of shares of Series A Junior Participating Preferred Stock entitled
to receive payment of a dividend or distribution declared thereon, which record
date shall be no more than 30 days prior to the date fixed for the payment
thereof.


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                  Section 3.  Voting Rights.  The holders of shares of Series A
Junior Participating Preferred Stock shall have the following voting rights:

                  (A) Subject to the provision for adjustment hereinafter set
forth, each share of Series A Junior Participating Preferred Stock shall entitle
the holder thereof to 1,000 votes on all matters submitted to a vote of the
shareholders of the Corporation. In the event the Corporation shall at any time
after the Rights Declaration Date (i) declare any dividend on Common Shares
payable in Common Shares, (ii) subdivide the outstanding Common Shares, or (iii)
combine the outstanding Common Shares into a smaller number of shares, then in
each such case the number of votes per share to which holders of shares of
Series A Junior Participating Preferred Stock were entitled immediately prior to
such event shall be adjusted by multiplying such number by a fraction the
numerator of which is the number of Common Shares outstanding immediately after
such event and the denominator of which is the number of Common Shares that were
outstanding immediately prior to such event.

                  (B) Except as otherwise provided herein or by law, the
holders of shares of Series A Junior Participating Preferred Stock and the
holders of Common Shares shall vote together as one class on all matters
submitted to a vote of shareholders of the Corporation.

                  (C) (i) If at any time dividends on any Series A Junior
         Participating Preferred Stock shall be in arrears in an amount equal to
         six (6) quarterly dividends thereon, the occurrence of such contingency
         shall mark the beginning of a period (herein called a "default period")
         which shall extend until such time when all accrued and unpaid
         dividends for all previous quarterly dividend periods and for the
         current quarterly dividend period on all shares of Series A Junior
         Participating Preferred Stock then outstanding shall have been declared
         and paid or set apart for payment. During each default period, all
         holders of Preferred Stock (including holders of the Series A Junior
         Participating Preferred Stock) with dividends in arrears in an amount
         equal to six (6) quarterly dividends thereon, voting as a class,

         irrespec-

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         tive of series, shall have the right to elect two (2) directors.

         (ii) During any default period, such voting right of the holders of
         Series A Junior Participating Preferred Stock may be exercised
         initially at a special meeting called pursuant to subpara- graph (iii)
         of this Section 3(C) or at any annual meeting of shareholders, and
         thereafter at annual meetings of shareholders, provided that such
         voting right shall not be exercised unless the holders of ten percent
         (10%) in number of shares of Preferred Stock outstanding shall be
         present in person or by proxy. The absence of a quorum of the holders
         of Common Shares shall not affect the exercise by the holders of
         Preferred Stock of such voting right. At any meeting at which the
         holders of Preferred Stock shall exercise such voting right initially
         during an existing default period, they shall have the right, voting as
         a class, to elect directors to fill such vacancies, if any, in the
         Board of Directors as may then exist up to two (2) directors or, if
         such right is exercised at an annual meeting, to elect two (2)
         directors. If the number which may be so elected at any special meeting
         does not amount to the required number, the holders of the Preferred
         Stock shall have the right to make such increase in the number of
         directors as shall be necessary to permit the election by them of the
         required number. After the holders of the Preferred Stock shall have
         exercised their right to elect directors in any default period and
         during the continuance of such period, the number of directors shall
         not be increased or decreased except by vote of the holders of
         Preferred Stock as herein provided or pursuant to the rights of any
         equity securities ranking senior to or pari passu with the Series A
         Junior Participating Preferred Stock.

         (iii) Unless the holders of Preferred Stock shall, during an existing
         default period, have previously exercised their right to elect
         directors, the Board of Directors may order, or, subject to the
         provisions of the Restated Certificate of Incorporation, as amended,
         any stockholder or shareholders owning in the aggregate not less than
         ten percent 

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         (10%) of the total number of shares of Preferred Stock outstanding,
         irrespective of series, may request, the calling of special meeting of
         the holders of Preferred Stock, which meeting shall thereupon be called
         by the President, a Vice-President or the Secretary of the Corporation.
         Notice of such meeting and of any annual meeting at which holders of
         Preferred Stock are entitled to vote pursuant to this Paragraph
         (C)(iii) shall be given to each holder of record of Preferred Stock by

         mailing a copy of such notice to him or her at his or her last address
         as the same appears on the books of the Corporation. Such meeting shall
         be called for a time not earlier than 20 days and not later than 60
         days after such order or request or in default of the calling of such
         meeting within 60 days after such order or request, such meeting may be
         called on similar notice by any shareholder or shareholders owning in
         the aggregate not less than ten percent (10%) of the total number of
         shares of Preferred Stock outstanding. Notwithstanding the provisions
         of this Paragraph (C)(iii), no such special meeting shall be called
         during the period within 60 days immediately preceding the date fixed
         for the next annual meeting of the shareholders.


                           (iv)  In any default period, the holders of Common
         Shares, and other classes of stock of the Corporation if applicable,
         shall continue to be entitled to elect the whole number of directors
         until the holders of Preferred Stock shall have exercised their right
         to elect two (2) directors voting as a class, after the exercise of
         which right (x) the directors so elected by the holders of Preferred
         Stock shall continue in office until their successors shall have been
         elected by such holders or until the expiration of the default period,
         and (y) any vacancy in the Board of Directors may (except as provided
         in Paragraph (C)(ii) of this Section 3) be filled by vote of a majority
         of the remaining directors theretofore elected by the hold-

                                      A-6



         ers of the class of stock which elected the Director whose office shall
         have become vacant. References in this Paragraph (C) to directors
         elected by the holders of particular class of stock shall include
         directors elected by such directors to fill vacancies as provided in
         clause (y) of the foregoing sentence.

                           (v) Immediately upon the expiration of a default
         period, (x) the right of the holders of Preferred Stock as a class to
         elect directors shall cease, (y) the term of any directors elected by
         the holders of Preferred Stock as a class shall terminate, and (z) the
         number of directors shall be such number as may be provided for in the
         Restated Certificate of Incorporation or By-laws irrespective of any
         increase made pursuant to the provisions of Paragraph (C)(ii) of this
         Section 3 (such number being subject, however, to change thereafter in
         any manner provided by law or in the Restated Certificate of
         Incorporation or By-Laws). Any vacancies in the Board of Directors
         effected by the provisions of clauses (y) and (z) in the preceding
         sentence may be filled by a majority of the remaining directors.

                  (D) Except as set forth herein, holders of Series A Junior
Participating Preferred Stock shall have no special voting rights and their
consent shall not be required (except to the extent they are entitled to vote
with holders of Common Shares as set forth herein) for taking any corporate
action.


                  Section 4.  Certain Restrictions.

                  (A) Whenever quarterly dividends or other dividends or
distributions payable on the Series A Junior Participating Preferred Stock as
provided in Section 2 are in arrears, thereafter and until all accrued and
unpaid dividends and distributions, whether or not declared, on shares of
Series A Junior Participating Preferred Stock outstanding shall have been paid
in full, the Corporation shall not 

                                    (i)  declare or pay dividends on, make any
         other distributions on, or redeem or purchase or otherwise acquire for
         consideration any shares of stock ranking junior (either as to
         dividends or upon liquidation, dissolution or winding up) to the Series
         A Junior Participating Preferred Stock;

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                                    (ii) declare or pay dividends on or make any
         other distributions on any shares of stock ranking on a parity (either
         as to dividends or upon liquidation, dissolution or winding up) with
         the Series A Junior Participating Preferred Stock, except dividends
         paid ratably on the Series A Junior Participating Preferred Stock and
         all such parity stock on which dividends are payable or in arrears in
         proportion to the total amounts to which the holders of all such shares
         are then entitled;

                                    (iii) redeem or purchase or otherwise
         acquire for consideration shares of any stock ranking on a parity
         (either as to dividends or upon liquidation, dissolution or winding up)
         with the Series A Junior Participating Preferred Stock, provided that
         the Corporation may at any time redeem, purchase or otherwise acquire
         shares of any such parity stock in exchange for shares of any stock of
         the Corporation ranking junior (either as to dividends or upon
         dissolution, liquidation or winding up) to the Series A Junior
         Participating Preferred Stock; or

                                    (iv)  purchase or otherwise acquire for con-
         sideration any shares of Series A Junior Participating Preferred Stock,
         or any shares of stock ranking on a parity with the Series A Junior
         Participating Preferred Stock, except in accordance with a purchase
         offer made in writing or by publication (as determined by the Board of
         Directors) to all holders of such shares upon such terms as the Board
         of Directors, after consideration of the respective annual dividend
         rates and other relative rights and preferences of the respective
         series and classes, shall determine in good faith will result in fair
         and equitable treatment among the respective series or classes.

                  (B) The Corporation shall not permit any subsidiary of the
Corporation to purchase or otherwise acquire for consideration any shares of
stock of the Corporation unless the Corporation could, under Paragraph (A) of
this Section 4, purchase or otherwise acquire such shares at such time and in
such manner.


                                      A-8



                  Section 5. Reacquired Shares. Any shares of Series A Junior
Participating Preferred Stock purchased or otherwise acquired by the
Corporation in any manner whatsoever shall be retired and cancelled promptly
after the acquisition thereof. All such shares shall upon their cancellation
become authorized but unissued shares of Preferred Stock and may be reissued as
part of a new series of Preferred Stock to be created by resolution or
resolutions of the Board of Directors, subject to the conditions and
restrictions on issuance set forth herein.

                  Section 6. Liquidation, Dissolution or Winding Up. (A) Upon
any liquidation (voluntary or otherwise), dissolution or winding up of the
Corporation, no distribution shall be made to the holders of shares of stock
ranking junior (either as to dividends or upon liquidation, dissolution or
winding up) to the Series A Junior Participating Preferred Stock unless, prior
thereto, the holders of shares of Series A Junior Participating Preferred Stock
shall have received an amount equal to 1,000 times the Exercise Price, plus an
amount equal to accrued and unpaid dividends and distributions thereon, whether
or not declared, to the date of such payment (the "Series A Liquidation
Preference"). Following the payment of the full amount of the Series A
Liquidation Preference, no additional distributions shall be made to the
holders of shares of Series A Junior Participating Preferred Stock unless,
prior thereto, the holders of Common Shares shall have received an amount per
share (the "Common Adjustment") equal to the quotient obtained by dividing (i)
the Series A Liquidation Preference by (ii) 1,000 (as appropriately adjusted as
set forth in subparagraph (C) below to reflect such events as stock splits,
stock dividends and recapitalizations with respect to the Common Shares) (such
number in clause (ii), the "Adjustment Number"). Following the payment of the
full amount of the Series A Liquidation Preference and the Common Adjustment in
respect of all outstanding shares of Series A Junior Participating Preferred
Stock and Common Shares, respectively, holders of Series A Junior Participating
Preferred Stock and holders of Common Shares shall receive their ratable and
proportionate share of the remaining assets to be distributed in the ratio of
the Adjustment Number to 1 with respect to such Preferred Stock and Common
Shares, on a per share basis, respectively.

                  (B) In the event, however, that there are not sufficient
assets available to permit payment in full of 


                                      A-9




the Series A Liquidation Preference and the liquidation preferences of all other
series of preferred stock, if any, which rank on a parity with the Series A
Junior Participating Preferred Stock, then such remaining assets shall be
distributed ratably to the holders of such parity shares inproportion to their
respective liquidation preferences. In the event, however, that there are not

sufficient assets available to permit payment in full of the Common Adjustment,
then such remaining assets shall be distributed ratably to the holders of Common
Shares.

                  (C) In the event the Corporation shall at any time after the
Rights Declaration Date (i) declare any dividend on Common Shares payable in
Common Shares, (ii) subdivide the outstanding Common Shares, or (iii) combine
the outstanding Common Shares into a smaller number of shares, then in each
such case the Adjustment Number in effect immediately prior to such event shall
be adjusted by multiplying such Adjustment Number by a fraction the numerator
of which is the number of Common Shares outstanding immediately after such
event and the denominator of which is the number of Common Shares that were
outstanding immediately prior to such event.

                  Section 7. Consolidation, Merger, etc. In case the
Corporation shall enter into any consolidation, merger, combination or other
transaction in which the Common Shares are exchanged for or changed into other
stock or securities, cash and/or any other property, then in any such case the
shares of Series A Junior Participating Preferred Stock shall at the same time
be similarly exchanged or changed in an amount per share (subject to the
provision for adjustment hereinafter set forth) equal to 1,000 times the
aggregate amount of stock, securities, cash and/or any other property (payable
in kind), as the case may be, into which or for which each Common Shares is
changed or exchanged. In the event the Corporation shall at any time after the
Rights Declaration Date (i) declare any dividend on Common Shares payable in
shares of Common Shares, (ii) subdivide the outstanding Common Shares, or (iii)
combine the outstanding Common Shares into a smaller number of shares, then in
each such case the amount set forth in the preceding sentence with respect to
the exchange or change of shares of Series A Junior Participating Preferred
Stock shall be adjusted by multiplying such amount by a fraction the numerator
of which is the number of Common Shares outstanding immediately after such
event and the denominator 

                                     A-10



of which is the number of shares of Common Shares that were outstanding
immediately prior to such event.

                  Section 8. No Redemption. The shares of Series A Junior
Participating Preferred Stock shall not be redeemable.

                  Section 9. Ranking. The Series A Junior Preferred Stock shall
rank junior to all other series of the Corporation's Preferred Stock as to the
payment of dividends and the distribution of assets, unless the terms of any
such series shall provide otherwise.

                  Section 10. Amendment. The Restated Certificate of
Incorporation, as amended, of the Corporation shall not be further amended in
any manner which would materially alter or change the powers, preferences or
special rights of the Series A Junior Participating Preferred Stock so as to
affect them adversely without the affirmative vote of the holders of a majority
or more of the outstanding shares of Series A Junior Participating Preferred

Stock, voting separately as a class.

                  Section 11. Fractional Shares. Series A Junior Participating
Preferred Stock may be issued in fractions of a share which shall entitle the
holder, in proportion to such holders fractional shares, to exercise voting
rights, receive dividends, participate in distributions and to have the benefit
of all other rights of holders of Series A Junior Participating Preferred
Stock.

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                  5. The manner in which the foregoing amendment of the
Certificate of Incorporation was authorized is a follows: The Board of
Directors of the Corporation authorized the amendment under the authority
vested in said Board under the provisions of the Certificate of Incorporation
and of Section 502 of the Business Corporation Law.


                  IN WITNESS WHEREOF, we have subscribed this document on the
date set opposite each of our names below and do hereby affirm, under the
penalties of perjury, that the statements contained therein have been examined
by us and are true and correct.

Date:  October 18, 1996



                                                /s/       Leonard S. Schleifer
                                                ------------------------------
                                                Name:     Leonard S. Schleifer
                                                Title:    President



                                                /s/ 
                                                ------------------------------
                                                Name:     Paul Lubetkin
                                                Title:    Secretary


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